Poly vinyl alcohol-CeO2 nanocomposite films: a promising material for NO2 sensors at high temperatures

Abstract

Nanoparticles of CeO2 were dispersed in Poly vinyl Alcohol to form nanocomposite films of various concentrations. Thick films of thickness around 100 μm were prepared by solution casting and pure PVA, PVA-2.5 wt% CeO2 and PVA-25 wt% CeO2 films were tested for their response as sensors to various gases. It was found that the PVA-2.5 wt% CeO2 film showed the best response of nearly 40% increase in resistance to 100 ppm of NO2 gas at 423 K. This indicated that it could be useful as a high temperature sensor for NO2 gas. Three of the above samples were also prepared by spin coating technique as thin films of thickness 1 μm, 5 μm and 50 μm, on a glass substrate and tested for sensing action of the same gases at 3 ppm concentration. It was seen that 2.5 wt% CeO2 film of 1 μm thickness gave the best response of 16% increase for NO2 gas, amongst all the films. The increase in resistance of the films in the presence of NO2 gas is due to chemisorption on the CeO2 nano fillers and the mechanism seems to be effective even at low concentration of the filler. The results of sensing in these films are better than that of other similar materials and suggest that they can be used as high temperature sensors.